The error message is clear. It means that the clearance between the tracks when you increased their widths are getting small that it violates the clearance settings that is set in your design rule.
Try to check your setting. In PADS Layout, Menu Setup/Design Rules then click the Default box. In the Default Rules dialog box, click Clearance. In this window, you will see different clearance settings: Trace-trace, via-via, etc.
To prevent the error message you encountered, decrease the trace-trace clearance.
Another solution to this, maybe not a proper solution, just for the error not to appear anymore is to disable the clearance DRC in PADS Router.
You can do this by going to Tools/DRC Settings and uncheck the enable box for the clearance. This way you will not encounter anymore the error.
As I've said, the correct way to do this is the previous solution.
Hope I helped!
thank you so much